This application claims priority of 199 02 920.2, filed Jan. 26, 1999, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a reciprocating piston engine with a crankshaft received in bearings and a first-order harmonic balancer and a secondary harmonic balancer (Lanchester balancer) with one or more shafts received in bearings being enclosed in a crankshaft housing and with the bearings of the crankshaft and/or the bearings of the Lanchester shafts consisting of at least one upper bearing part and one lower bearing part.
A drive device is already known for a motor vehicle with an engine, a crankshaft, and a transmission (German Patent Document DE 41 34 399 A1) which shows a crankshaft received in bearings and a first-order harmonic balancer as well as a second-order harmonic balancer, to which a plurality of shafts received in bearings belong that are received in a crankshaft housing. The bearing housing of the second-order harmonic balancer (Lanchester balancer) is connected releasably with the crankshaft housing of the crankshaft by a flange connection. The separate design of the suspended Lanchester housing leads to a considerable amount of work being involved in manufacturing the bearings of the crankshaft and the bearings of the Lanchester balancer, especially because the individual parts must be clamped very frequently when machining the bearings. A considerable amount of work is also required to machine the bearings to create a precise seat between the bearings of the crankshaft and/or bearings of the Lanchester balancer.
Accordingly, a goal of the invention is to design or manufacture the upper bearing part and the bearing cover and the lower bearing part of a shaft so that no finishing of the flange areas is required.
This goal is achieved according to the invention by virtue of the fact that at least the flange surfaces of the upper and lower bearing parts that abut one another have a fracture surface formed by cracking. As a result, the flange surfaces formed by cracking using this machining process need not be finished any further and the cracked flange surface makes possible very good attachment between the bearing parts to be joined.
It is also advantageous that, as already mentioned, the flange surfaces formed by cracking remain unfinished after cracking. Unevennesses and the roughened flange surfaces of the bearing parts that fit together permit a very accurate adjustment and hence an exact seat for the one bearing part to be mounted on the other bearing part.
An additional possibility according to an improvement on the device according to preferred embodiments of the invention is that the glagn surfaces formed by cracking have a small notch in the vicinity of their fracture for the cracking process. Notching or grooving can be performed by means of a laser and ensures that at the location of the groove during the fracturing process, in other words when the lower bearing part is broken off from the upper bearing part, a crack surface forms very precisely at this point which then corresponds to the flange surface of the bearing. If the two corresponding bearing parts are joined once again after the shafts have been installed, they can be adjusted in simple fashion since the two fracture surfaces or crack surfaces that belong together join again precisely. As a result, the bearing resume the same position as before the cracking process. The result is a very precise seat for the lower bearing part to joined to the upper bearing part.
In certain preferred embodiments of the invention, it is advantageous that the upper bearing part of the Lanchester shaft with which the lower bearing part is releasably connected, also has a flange surface or first crack plane formed by cracking and that, as already mentioned, the upper bearing part of the Lanchester shaft with its cracked flange surface abuts the cracked flange surface of the lower bearing part of the crankshaft.
According to certain preferred embodiments of the device according to the invention, provision is made such that the second crack plate or parting plane between the upper bearing part and the lower bearing part of the Lanchester shaft is formed for second-order balancing.
It is especially advantageous for certain preferred embodiments of the present invention to provide that the second crack plane of the flange surface of the upper bearing part and the lower bearing part correspond, the latter being in approximately the same plane as the parting plane between the crankcase and the crankshaft housing.
In conjunction with the design and arrangement according to certain preferred embodiments of the invention, it is advantageous for the crack surface to have a groove depth between 0.01 mm and 0.1 mm.
It is also advantageous according to certain preferred embodiments of the invention to provide that at least one lower bearing part of the bearing of the crankshaft is connected in one piece by means of one bearing of the Lanchester shaft or forms a structural unit. As a result, assembly time is reduced and the machining time for the bearing part is reduced since the workpiece needs to be clamped only a few times.
It is also advantageous according to certain preferred embodiments of the invention to provide that the one-piece part with the lower bearing part of the bearing of the crankshaft is connected on one side to an upper bearing part of the crankshaft and a lower bearing part of the Lanchester shaft is attached on the other side.
It is also advantageous in this respect according to certain preferred embodiments of the invention to provide that the one-piece part of the crankshaft, in addition to the two top bearing parts for the two Lanchester shafts, has an additional lower bearing part for a third Lanchester shaft.